Use of methods for specifying the target difference in randomised controlled trial sample size calculations : Two surveys of trialists' practice

© The Author(s), 2014.Peer reviewedPublisher PD

Randomised trial of glutamine, selenium, or both, to supplement parenteral nutrition for critically ill patients

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The NAtional randomised controlled Trial of Tonsillectomy IN Adults (NATTINA) : a clinical and cost-effectiveness study: study protocol for a randomised control trial

This project is funded by the National Institute for Health Research (NIHR) Health Technology Assessment (HTA) Programme (project number 12/146/06).BACKGROUND: The role of tonsillectomy in the management of adult tonsillitis remains uncertain and UK regional variation in tonsillectomy rates persists. Patients, doctors and health policy makers wish to know the costs and benefits of tonsillectomy against conservative management and whether therapy can be better targeted to maximise benefits and minimise risks of surgery, hence maximising cost-effective use of resources. NATTINA incorporates the first attempt to map current NHS referral criteria against other metrics of tonsil disease severity. METHODS/DESIGN: A UK multi-centre, randomised, controlled trial for adults with recurrent tonsillitis to compare the clinical and cost-effectiveness of tonsillectomy versus conservative management. An initial feasibility study comprises qualitative interviews to investigate the practicality of the protocol, including willingness to randomise and be randomised. Approximately 20 otolaryngology staff, 10 GPs and 15 ENT patients will be recruited over 5 months in all 9 proposed main trial participating sites. A 6-month internal pilot will then recruit 72 patients across 6 of the 9 sites. Participants will be adults with recurrent acute tonsillitis referred by a GP to secondary care. Randomisation between tonsillectomy and conservative management will be according to a blocked allocation method in a 1:1 ratio stratified by centre and baseline disease severity. If the pilot is successful, the main trial will recruit a further 528 patients over 18 months in all 9 participating sites. All participants will be followed up for a total of 24 months, throughout which both primary and secondary outcome data will be collected. The primary outcome is the number of sore throat days experienced over the 24-month follow-up. The pilot and main trials include an embedded qualitative process evaluation. DISCUSSION: NATTINA is designed to evaluate the relative effectiveness and efficiency of tonsillectomy versus conservative management in patients with recurrent sore throat who are eligible for surgery. Most adult tonsil disease and surgery has an impact on economically active age groups, with individual and societal costs through loss of earnings and productivity. Avoidance of unnecessary operations and prioritisation of those individuals likely to gain most from tonsillectomy would reduce costs to the NHS and society. TRIAL REGISTRATION: ISRCTN55284102, Date of Registration: 4 August 2014.Publisher PDFPeer reviewe

Clinical effectiveness and cost-effectiveness of immediate angioplasty for acute myocardial infarction : systematic review and economic evaluation

Background The blockage of a coronary artery (coronary thrombosis) can lead to a heart attack (acute myocardial infarction). There are several ways of trying to overcome this blockage. The methods include drug treatment to dissolve the clot (thrombolysis) and physical intervention, either by passing a catheter into the affected artery [angioplasty or percutaneous coronary intervention (PCI)], or bypassing the blocked section by cardiac surgery [coronary artery bypass grafting (CABG)]. Thrombolysis can be given in the community before the patient is sent to hospital, or delayed until after admission. Prehospital thrombolysis is not common in the UK. Immediate angioplasty is not routinely available in the UK at present; it is much more common in the USA. Objectives To review the clinical evidence comparing immediate angioplasty with thrombolysis, and to consider whether it would be cost-effective. Methods This report was based on a systematic review of the evidence of clinical effectiveness and an economic analysis of cost-effectiveness based on the clinical review and on cost data from published sources and de novo data collection. Data sources The search strategy searched six electronic databases (including Medline, Cochrane Library and EMBASE), with English-language limits, for the periods up to December 2002. Bibliographies of related papers were assessed for relevant studies and experts contacted for advice and peer review, and to identify additional published and unpublished references. Study selection For clinical effectiveness, a comprehensive review of randomised controlled trials (RCTs) was used for efficacy, and a selection of observational studies such as case series or audit data for effectiveness safety in routine practice. RCTs of thrombolysis were used to assess the relative value of prehospital and hospital thrombolysis. Observational studies were used to assess the representativeness of patients in the RCTs, and to determine whether different groups have different capacity to benefit. They were used to assess the implications of wider diffusion of the technology away from major centres. Data extraction Data extraction and quality assessment were undertaken by one reviewer and checked by a second reviewer, with any disagreements resolved through discussion. The quality of systematic reviews, RCTs, controlled clinical trials and economic studies was assessed using criteria recommended by the NHS Centre for Reviews and Dissemination (University of York). Study synthesis Clinical effectiveness was synthesised through a narrative review with full tabulation of results of all included studies and a meta-analysis to provide a precise estimate of absolute clinical benefit. Consideration was given to the effect of the growing use of stents. The economic modelling adopted an NHS perspective to develop a decision-analytical model of cost-effectiveness focusing on opportunity costs over the short term (6 months). Results and conclusion Number and quality of studies, and summary of benefits There were several good-quality systematic reviews, including a Cochrane review, as well as an individual patient meta-analysis and a number of recent trials not included in the reviews. The results were consistent in showing an advantage of immediate angioplasty over hospital thrombolysis. The updated meta-analysis showed that mortality is reduced by about one-third, from 7.6% to 4.9% in the first 6 months, and by about the same in studies of up to 24 months. Reinfarction is reduced by over half, from 7.6% to 3.1%. Stroke is reduced by about two-thirds, from 2.3% with thrombolysis to 0.7% with PCI, with the difference being due to haemorrhagic stroke. The need for CABG is reduced by about one-third, from 13.2% to 8.4%. Caution is needed in interpreting the older trials, as changes such as an increase in stenting and the use of the glycoprotein IIb/IIa inhibitors may improve the results of PCI. There is little evidence comparing prehospital thrombolysis with immediate PCI. One good quality study from France showed that prehospital thrombolysis with PCI in those in whom thrombolysis failed was as good as universal PCI. Research on thrombolysis followed by PCI, known as facilitated PCI, is underway, but results are not yet available. Further caveats are needed. Trials may be done in select centres and results may not be as good in lower volume centres, or out of normal working hours. In addition, much of the marginal mortality benefit of PCI over hospital thrombolysis may be lost if door-to-balloon time were more than 1 hour longer than door-to-needle time. Conversely, within the initial 6 hours, the later patients present, the greater the relative advantage of PCI. Cost-effectiveness If both interventions were routinely available, the economic analysis favours PCI, given the assumptions of the model. Results suggest that PCI is more cost-effective than thrombolysis, providing additional benefits in health status at some extra cost and an incremental cost per unit change in health status under the £30,000 threshold in most instances. In the longer term, the cost difference is expected to be reduced because of higher recurrence and reintervention rates among those who had thrombolysis. The model is not particularly sensitive to variations in probabilities from the clinical effectiveness analysis. However, very few units in England could offer a routine immediate PCI service at present, and there would be considerable resource implications of setting up such services. Without a detailed survey of existing provision, it is not possible to quantify the implications, but they include both capital and revenue: an increase in catheter laboratory provision and running costs. The greatest problem would be staffing, and that would take some years to resolve. A gradual incrementalist approach based on clinical networks, with transfer to centres able to offer PCI, could be used. In rural areas, one option could be to promote an increase in prehospital thrombolysis, with PCI for thrombolysis failures. Need for further research There is a need for economic data on the long-term consequences of the treatment, the quality of life of patients after treatment and the effects of PCI following thrombolysis failure

Systematic review of the clinical effectiveness and cost-effectiveness and economic modelling of minimal incision total hip replacement approaches in the management of arthritic disease of the hip

Objectives: To assess the clinical effectiveness and cost-effectiveness of minimal incision approaches to total hip replacement (THR) for arthritis of the hip. Data sources: Major electronic databases were searched from 1966 to 2007. Relevant websites were also examined and experts in the field were consulted. Review methods: Studies of minimal (one or two) incision THR compared with standard THR were assessed for inclusion in the review of clinical effectiveness. A systematic review of economic evaluations comparing a minimal incision approach to standard THR was also performed and the estimates from the systematic review of clinical effectiveness were incorporated into an economic model. Utilities data were sourced to estimate quality-adjusted life-years (QALYs). Due to lack of data, no economic analysis was conducted for the two mini-incision surgical method. Results: Nine randomised controlled trials (RCTs), 17 non-randomised comparative studies, six case series and one registry were found to be useful for the comparison of single mini-incision THR with standard THR. One RCT compared two mini-incision THR with standard THR, and two RCTs, five non-randomised comparative studies and two case series compared two mini-incision with single mini-incision THR. The RCTs were of moderate quality. Most had fewer than 200 patients and had a follow-up period of less than 1 year. The single mini-incision THR may have some perioperative advantages, e.g. blood loss [weighted mean difference (WMD) –57.71 ml, p £30,000) if recovery was 1.5 weeks faster. A threshold analysis around risk of revision showed, using the same cost per QALY threshold, mini-incision THR would have to have no more than a 7.5% increase in revisions compared with standard THR for it to be no longer considered cost-effective (one more revision for every 200 procedures performed). Further sensitivity analysis involved relaxing assumptions of equal long-term outcomes where possible. and broadly similar results to the base-case analysis were found in this and further sensitivity analyses. Conclusions: Compared with standard THR, minimal incision THR has small perioperative advantages in terms of blood loss and operation time. It may offer a shorter hospital stay and quicker recovery. It appears to have a similar procedure cost to standard THR, but evidence on its longer term performance is very limited. Further long-term follow-up data on costs and outcomes including analysis of subgroups of interest to the NHS would strengthen the current economic evaluation.The Health Services Research Unit and the Health Economics Research Unit are both core funded by the Chief Scientist Office of the Scottish Government Health Directorates.Peer reviewedPublisher PD

Effect of multivitamin and multimineral supplementation on cognitive function in men and women aged 65 years and over : a randomised controlled trial

Background: Observational studies have frequently reported an association between cognitive function and nutrition in later life but randomised trials of B vitamins and antioxidant supplements have mostly found no beneficial effect. We examined the effect of daily supplementation with 11 vitamins and 5 minerals on cognitive function in older adults to assess the possibility that this could help to prevent cognitive decline. Methods: The study was carried out as part of a randomised double blind placebo controlled trial of micronutrient supplementation based in six primary care health centres in North East Scotland. 910 men and women aged 65 years and over living in the community were recruited and randomised: 456 to active treatment and 454 to placebo. The active treatment consisted of a single tablet containing eleven vitamins and five minerals in amounts ranging from 50–210 % of the UK Reference Nutrient Intake or matching placebo tablet taken daily for 12 months. Digit span forward and verbal fluency tests, which assess immediate memory and executive functioning respectively, were conducted at the start and end of the intervention period. Risk of micronutrient deficiency at baseline was assessed by a simple risk questionnaire. Results: For digit span forward there was no evidence of an effect of supplements in all participants or in sub-groups defined by age or risk of deficiency. For verbal fluency there was no evidence of a beneficial effect in the whole study population but there was weak evidence for a beneficial effect of supplementation in the two pre-specified subgroups: in those aged 75 years and over (n 290; mean difference between supplemented and placebo groups 2.8 (95% CI -0.6, 6.2) units) and in those at increased risk of micronutrient deficiency assessed by the risk questionnaire (n 260; mean difference between supplemented and placebo groups 2.5 (95% CI -1.0, 6.1) units). Conclusion: The results provide no evidence for a beneficial effect of daily multivitamin and multimineral supplements on these domains of cognitive function in community-living people over 65 years. However, the possibility of beneficial effects in older people and those at greater risk of nutritional deficiency deserves further attention.Peer reviewedPublisher PD

Choosing the target difference ('effect size') for a randomised controlled trial - DELTA(2) guidance protocol

BACKGROUND: A key step in the design of a randomised controlled trial (RCT) is the estimation of the number of participants needed. By far the most common approach is to specify a target difference and then estimate the corresponding sample size; this sample size is chosen to provide reassurance that the trial will have high statistical power to detect such a difference between the randomised groups (at the planned statistical significance level). The sample size has many implications for the conduct of the study, as well as carrying scientific and ethical aspects to its choice. Despite the critical role of the target difference for the primary outcome in the design of an RCT, the manner in which it is determined has received little attention. This article reports the protocol of the Difference ELicitation in TriAls (DELTA(2)) project, which will produce guidance on the specification and reporting of the target difference for the primary outcome in a sample size calculation for RCTs. METHODS/DESIGN: The DELTA(2) project has five components: systematic literature reviews of recent methodological developments (stage 1) and existing funder guidance (stage 2); a Delphi study (stage 3); a 2-day consensus meeting bringing together researchers, funders and patient representatives, as well as one-off engagement sessions at relevant stakeholder meetings (stage 4); and the preparation and dissemination of a guidance document (stage 5). DISCUSSION: Specification of the target difference for the primary outcome is a key component of the design of an RCT. There is a need for better guidance for researchers and funders regarding specification and reporting of this aspect of trial design. The aim of this project is to produce consensus based guidance for researchers and funders

Systematic review of economic evaluations and cost analyses of guideline implementation strategies

Objectives To appraise the quality of economic studies undertaken as part of evaluations of guideline implementation strategies; determine their resources use; and recommend methods to improve future studies. Methods Systematic review of economic studies undertaken alongside robust study designs of clinical guideline implementation strategies published (1966-1998). Studies assessed against the BMJ economic evaluations guidelines for each stage of the guideline process (guideline development, implementation and treatment). Results 235 studies were identified, 63 reported some information on cost. Only 3 studies provided evidence that their guideline was effective and efficient. 38 reported the treatment costs only, 12 implementation and treatment costs, 11 implementation costs alone, and two guideline development, implementation and treatment costs. No study gave reasonably complete information on costs. Conclusions Very few satisfactory economic evaluations of guideline implementation strategies have been performed. Current evaluations have numerous methodological defects and rarely consider all relevant costs and benefits. Future evaluations should focus on evaluating the implementation of evidence based guidelines. Keywords: Cost-effectiveness analysis, physician (or health care professional) behaviour, practice guidelines, quality improvement, systematic review.Peer reviewedAuthor versio

Best-practice prevention alone or with conventional or biological caries management for 3- to 7-year-olds:the FiCTION three-arm RCT

Background Historically, lack of evidence for effective management of decay in primary teeth has caused uncertainty, but there is emerging evidence to support alternative strategies to conventional fillings, which are minimally invasive and prevention orientated. Objectives The objectives were (1) to assess the clinical effectiveness and cost-effectiveness of three strategies for managing caries in primary teeth and (2) to assess quality of life, dental anxiety, the acceptability and experiences of children, parents and dental professionals, and caries development and/or progression. Design This was a multicentre, three-arm parallel-group, participant-randomised controlled trial. Allocation concealment was achieved by use of a centralised web-based randomisation facility hosted by Newcastle Clinical Trials Unit. Setting This trial was set in primary dental care in Scotland, England and Wales. Participants Participants were NHS patients aged 3–7 years who were at a high risk of tooth decay and had at least one primary molar tooth with decay into dentine, but no pain/sepsis. Interventions Three interventions were employed: (1) conventional with best-practice prevention (local anaesthetic, carious tissue removal, filling placement), (2) biological with best-practice prevention (sealing-in decay, selective carious tissue removal and fissure sealants) and (3) best-practice prevention alone (dietary and toothbrushing advice, topical fluoride and fissure sealing of permanent teeth). Main outcome measures The clinical effectiveness outcomes were the proportion of children with at least one episode (incidence) and the number of episodes, for each child, of dental pain or dental sepsis or both over the follow-up period. The cost-effectiveness outcomes were the cost per incidence of, and cost per episode of, dental pain and/or dental sepsis avoided over the follow-up period. Results A total of 72 dental practices were recruited and 1144 participants were randomised (conventional arm, n = 386; biological arm, n = 381; prevention alone arm, n = 377). Of these, 1058 were included in an intention-to-treat analysis (conventional arm, n = 352; biological arm, n = 352; prevention alone arm, n = 354). The median follow-up time was 33.8 months (interquartile range 23.8–36.7 months). The proportion of children with at least one episode of pain or sepsis or both was 42% (conventional arm), 40% (biological arm) and 45% (prevention alone arm). There was no evidence of a difference in incidence or episodes of pain/sepsis between arms. When comparing the biological arm with the conventional arm, the risk difference was –0.02 (97.5% confidence interval –0.10 to 0.06), which indicates, on average, a 2% reduced risk of dental pain and/or dental sepsis in the biological arm compared with the conventional arm. Comparing the prevention alone arm with the conventional arm, the risk difference was 0.04 (97.5% confidence interval –0.04 to 0.12), which indicates, on average, a 4% increased risk of dental pain and/or dental sepsis in the prevention alone arm compared with the conventional arm. Compared with the conventional arm, there was no evidence of a difference in episodes of pain/sepsis among children in the biological arm (incident rate ratio 0.95, 97.5% confidence interval 0.75 to 1.21, which indicates that there were slightly fewer episodes, on average, in the biological arm than the conventional arm) or in the prevention alone arm (incident rate ratio 1.18, 97.5% confidence interval 0.94 to 1.48, which indicates that there were slightly more episodes in the prevention alone arm than the conventional arm). Over the willingness-to-pay values considered, the probability of the biological treatment approach being considered cost-effective was approximately no higher than 60% to avoid an incidence of dental pain and/or dental sepsis and no higher than 70% to avoid an episode of pain/sepsis. Conclusions There was no evidence of an overall difference between the three treatment approaches for experience of, or number of episodes of, dental pain or dental sepsis or both over the follow-up period

A core outcome set for localised prostate cancer effectiveness trials

Objective: To develop a core outcome set (COS) applicable for effectiveness trials of all interventions for localised prostate cancer. Background: Many treatments exist for localised prostate cancer, although it is unclear which offers the optimal therapeutic ratio. This is confounded by inconsistencies in the selection, definition, measurement and reporting of outcomes in clinical trials. Subjects and methods: A list of 79 outcomes was derived from a systematic review of published localised prostate cancer effectiveness studies and semi-structured interviews with 15 prostate cancer patients. A two-stage consensus process involving 118 patients and 56 international healthcare professionals (HCPs) (cancer specialist nurses, urological surgeons and oncologists) was undertaken, consisting of a three-round Delphi survey followed by a face-to-face consensus panel meeting of 13 HCPs and 8 patients. Results: The final COS included 19 outcomes. Twelve apply to all interventions: death from prostate cancer, death from any cause, local disease recurrence, distant disease recurrence/metastases, disease progression, need for salvage therapy, overall quality of life, stress urinary incontinence, urinary function, bowel function, faecal incontinence, sexual function. Seven were intervention-specific: perioperative deaths (surgery), positive surgical margin (surgery), thromboembolic disease (surgery), bothersome or symptomatic urethral or anastomotic stricture (surgery), need for curative treatment (active surveillance), treatment failure (ablative therapy), and side effects of hormonal therapy (hormone therapy). The UK-centric participants may limit the generalisability to other countries, but trialists should reason why the COS would not be applicable. The default position should not be that a COS developed in one country will automatically not be applicable elsewhere. Conclusion: We have established a COS for trials of effectiveness in localised prostate cancer, applicable across all interventions which should be measured in all localised prostate cancer effectiveness trials